Bug 705636

Summary:	MTRR logic makes 90% of RAM inaccessible
Product:	Red Hat Enterprise Linux 6	Reporter:	Philip Pokorny <ppokorny>
Component:	kernel	Assignee:	Prarit Bhargava <prarit>
Status:	CLOSED DUPLICATE	QA Contact:	Red Hat Kernel QE team <kernel-qe>
Severity:	high	Docs Contact:
Priority:	unspecified
Version:	6.1	CC:	arozansk, brian.macleod
Target Milestone:	rc
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-05-20 14:28:03 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:

Description Philip Pokorny 2011-05-17 23:47:23 UTC

Description of problem:

Booting 2.6.32-122 kernel on an AMD system gives this message:

WARNING: BIOS bug: CPU MTRRs don't cover all of memory, losing 29184MB of RAM.
------------[ cut here ]------------
WARNING: at arch/x86/kernel/cpu/mtrr/cleanup.c:1092 mtrr_trim_uncached_memory+0xx
2de/0x309() (Not tainted)
Hardware name: empty
Modules linked in:
Pid: 0, comm: swapper Not tainted 2.6.32-122.el6.x86_64 #1
Call Trace:
 [<ffffffff81066ee7>] ? warn_slowpath_common+0x87/0xc0
 [<ffffffff81066f3a>] ? warn_slowpath_null+0x1a/0x20
 [<ffffffff81bc9288>] ? mtrr_trim_uncached_memory+0x2de/0x309
 [<ffffffff81bc30f2>] ? setup_arch+0x4c4/0xacb
 [<ffffffff814d8ea5>] ? printk+0x41/0x44
 [<ffffffff81bbdbe7>] ? start_kernel+0xdc/0x424
 [<ffffffff81bbd33a>] ? x86_64_start_reservations+0x125/0x129
 [<ffffffff81bbd438>] ? x86_64_start_kernel+0xfa/0x109
---[ end trace a7919e7f17c0a725 ]---

This is a system with a newer AMD processor and the fix is available upstream in 3fdbf004c1706480a7c7fac3c9d836fa6df20d7d


Version-Release number of selected component (if applicable):

2.6.32-122

How reproducible:

100% Multiple systems with Interlagos CPU's

Steps to Reproduce:
1. Boot kernel
2. dmesg
3. free
  
Actual results:

Kernel BUG
no memory

Expected results:

No bug
All memory available.

Additional info:

Comment 1 Philip Pokorny 2011-05-17 23:48:57 UTC

I am told this was fixed in kernel 2.6.32-130, but I don't see that Red Hat Beta has any accessible repository (RHN, Yum, etc.) where I can download updated kernels.

Please provide a link to the latest Red Hat Beta kernel after 2.6.32-130 so that I can continue testing the Beta on this new hardware.

Thanks,
Phil P.

Comment 3 Prarit Bhargava 2011-05-20 14:28:03 UTC

Philip, RHEL6.1 has just been released and should resolve your problem.  Please reply back if RHEL6.1 does not fix your problem and reopen this BZ.

Thanks,

P.

*** This bug has been marked as a duplicate of bug 662238 ***